The (010) surface of α-MoO3, a DFT + U study

Abstract

We apply periodic density functional theory to α-MoO₃ and its (010) surface. The formation energy and structure of defects in the form of surface oxygen vacancies are found to depend critically on the treatment of electron localisation which is achieved in the periodic model using the DFT + U method. Calculated vibrational states for the defect free surface are found to agree well with surface science experimental data and we show that the molybdenyl stretching mode is shifted to a lower frequency in the neighbourhood of a terminal oxygen vacancy. Adsorption of molecular oxygen at the defect site can result in O₂, O₂⁻ or O₂²⁻ surface species depending on the geometry of adsorption.